Furnace draft-controller.



PATENTED FEB. 13, 1906.

. w. MGCLAVE'. FURNACE DRAFT CONTROLLER.

APPLICATION FILED NOV. 3, 1904.

' e SHEETS-SHEET 1.

al bouwgd No. 812,669. 1 PATENTED FEB. 13, 1906.

W: MQGLAVE.

FURNACE DRAFT CONTROLLER.

APPLICATION FILED NOV. 3, 1904.

6 SHEETS-SHEET 3.

WW jaww @3 1 means No. 812,669. v PATENTED FEB. 13, 1906.

w. MGGLAVE.

FURNACE DRAFT CONTROLLER.

APPLICATION FILED NOV. 3, 1904.

6 SHEETS-SHEET 4' umzwboz thaw/190 PATENTED FEB. 13, 1906.

w. MGGLAVEQ FURNACE DRAFT CONTROLLER.

APPLICATION FILED NOV. 3, 1904.

6 SHEETS-SHEBT 5.

PATENTED FEB. 13, 1906.

W MQGLAVE. FURNACE DRAFT CONTROLLER.

APPLIGATION FILED NOV. 3, 1904.

6 SHEETS-SHEET 6- 3 mazwbo'b UNITED sra'ras PATENT omen WILLIAM MoOLAVE,OF SORANTON, PENNSYLVANIA, ASSIGNOR TO Mo- OLAVE-BROOKS COMPANY, ACORPORATION OF PENNSYLVANIA.

FURNACE DRAFT-CONTROLLER.

Specification of Letters Patent.

Patented Feb. 13, 1906.

Application filed November 3, 1904;. Serial No. 231,251.

To all whom it may concern.

Be it known that I, WILLIAM MoCLAvE, a citizen of the United States,residing at Scranton, in the county of Lackawanna and State ofPennsylvania, have invented certain new and useful Improvements inFurnace Draft- Controllers; and I do hereby declare the following to bea full, clear, and exact descrip tion of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same.

This invention relates to improvements in pressure-regulators, and isdirected more particularly to mechanism for controlling the supply ofair to boiler-furnaces for governing the combustion therein, and therebycontrolling the pressure of steam generated in the boilers heated therebThe object in view is the provision of means which shall be extremelysensitive and at the same time be capable-of controlling the supply ofsteam at high pressure employed for producing forced draft.

A further object of the invention is the provision of a sensitivecontrolling means for steam-pressure, such controlling means beingadapted to be operated with very short movements, means being providedproducing relatively long movement and further means being provided fortransforming the long movements into short movements for increasing thepower thereof.

With these and further objects in view the invention comprises thecombination with a valve controlling the fiow of steam, a stem therefor,a piston connected with said stem, and a cylinder inclosing said piston,suitable ports being arranged for supplying steam to the piston forcausing actuation thereof for opening and closing said valve, thebalanced valves controlling the passage of steam within said ports, andmeans for effecting simultaneous actuation of said valves.

The invention further comprises the combination with a piston and acylinder inclosing the same, said cylinder being formed with ports forsupplying fluid under pressure to said piston, of balanced valves forcontrol ling the supply of fluid under pressure through said ports, thestroke of said valves being relatively short, power-supply means havinga relatively long stroke, and means for transmitting motion from saidpower-supply means to said valves, said transmitting means serving totransform the relatively long stroke of the power-supply means intorelatively short strokes of the valves with a corresponding increase inthe power relative to the decrease in the length of the stroke.

The invention further comprises certain other novel constructions,combinations, and arrangements of parts, as will be hereinafter fullydescribed and claimed.

In the accompanying drawings, Figure 1 represents a longitudinal centralsectional view through a controlling mechanism and a solenoid foractuating the same embodying the features of the present invention. Fig.2 represents a similar view of the controlling mechanism on an enlargedscale. Fig. 3 represents a view in side elevation of the parts shown inan assembled relation. Fig. 4 represents a top plan view of thecontrolling mechanism. Fig. 5 represents a view in side elevation of thecircuit-closing apparatus and pressure-gage for actuating the same. Fig.6 represents a side view of the same. Fig. 7 represents a top plan viewthereof.

Referring to the drawings by numerals, 1 indicates a steam supply pipeextending from any suitable source of supply to any desired point ofutilization, it being clearly apparent that the present invention is notto be limited to any particular art and while adapted especially forgoverning the. supply of steam employed for producing the forced draftof a furnace is by no means restricted to such use, but is susceptibleof employment wherever it is desired to effectually control the steam toany particular point by a highly sensitive mechanism. Thepipe 1,therefore, may be of any preferred type and has interposed in its lengtha suitable valve 2, preferably of the balanced type; but of course anycommon form of valve may be used. EX- tending from the valve 2 is itsstem 3, which projects upwardly through the usual packinggland of thevalve and through a packing-gland 4 of a cylinder 5, the upper end ofthe stem 3 carrying a piston-head 6 within the cylinder 5.

At each end of the cylinder 5 is formed a port 7, each of said portsserving both as an intake and an exhaust port, the outer end of theupper port 7 communicating with a valvechamber 8, which valve-chamber isadapted to be supplied with steam under pressure through the passage 9,formed in a plug 10,

threaded into the casing 11, of which the cylinder 5 is a part. Thecasing 11 is preferably supported by brackets 11, secured thereto orformed integral'therewithand engaging the casing of valve 2, each ofsaid brackets 11 being preferably formed of separable parts connected bya bolt or other suitable connecting means 11*. The plug 10 is formedwith a transverse passage 12, com- ,municating with any suitablepressure-supply pipe at 13, it being understood that the pressureordinarily used is relatively high, and the present improved apparatusis especially adapted for use under high pressure. The plug 10 isfurther formed with an annular groove 14, arranged in the samehorizontal plane with passage 12, so that steam supplied to passage 12will at the same time be permitted to pass about the plug 10 and will bedirected by-passage 14 into passage 15, said passages 14 and 15 beingformed in the casing 11 and the passage 15 communicating with thevalve-chamber 16, with which the lower port 7 communicates. The passage9 is formed with a valve-seat 17 at its lower end just outside thevalve-chamber 8, and a valve-stem 18 extends longitudinally through thepassage 9 and carries a valve 19 at its lower end in position forengaging the seat 17 when the stem 18 is at its uppermost position,whereby the passage 9 may be closed. The valve-stem 18 is of course ofless diameter than the passage 9 and when the valve 19 is off its seatwill permit the passage of steam into the chamber 8. The stem 18 extendsupwardly throughout the length of the plug 10, through a packing gland20, and upwardly into engagement with operating means hereinafterdescribed. An exhaustport21 communicateswiththevalve-chamber 8 justbeneath and preferably in line with the lower end of the passage 9 andis provided with a valve-seat 22, adapted to receive a valve 23, formedintegral with or suitably connected to the valve 19 in such manner thatwhenever the valve 19 is off its seat the valve 23 will be upon the seat22 and whenever the valve 19 is upon its seat the valve 23 will be offits seat, the length of the stroke of the valve-stem 18 being of coursesufficient for alternately bringing the valves 19 and 23 to theirrespective seats. The lower end of the exhaust-port 21 may communicatewith any suitable waste-pipe 24, or the exhaust may be disposed of inany other manner desired. The passage 15 is at its lower end of the samediameter as the passage 9, and the valve stem 25 extends longitudinallythroughout the passage 15, said stem 25 being of the same diameter asvalve-stem 18 and extending upwardly from the passage 15 through asuitable stufling-box 26 and beyond the stufiing-box to anoperating-lever, hereinafter described. The lower end of the valve-stem25 carries a valve 27, disposed within the valve-chamber 16 and adaptedto engage a seat 28, formed at the lower end of the passage 15.

A valve 29 is formed integral with or suitably secured to the valve 27and is positioned for en aging a seat 30, formed at the upper end 0 anexhaust-port 31, communicating with the valve-chamber 16. Theexhaustport 31 communicates with the waste-pipe 24 in a similar mannerto exhaust-port 21. The valves 27 and 29 are so disposed within thechamber 16 that when a sufficient stroke is imparted to the valve-stem25 one of said valves will be unseated and the'other seated, and thereverse stroke of the stem will produce a reverse action, one of saidvalves being always seated in a manner similar to the operation ofvalves 19 and 23. Now in order t at the piston 6 may be actuated whendesired and may be effectually controlled in its operation I haveprovided means for recipro- .cating the valve-stems 18 and 25alternately in opposite directions, so that when the valve ,23 is uponits seat 22 and fluid under pressure is being supplied to the upper endof the icylinder 5 the valve 29 must be off its seat-30 iand the lowerend of the cylinder thereby flopened to the exhaust. valve 27 andseating of connections between valve-stems 25 and 18 lwill produce anunseating of the valve 23 and @a seating of valve 19, whereby the upperend of the cylinder 5 is open to the exhaust and the lower end Theunseating of the valve 29 through the supplied with fluid underpressure. It is to be noted that the pressure uponvalves 19 and 27 isequal, and said valves are thus balanced with respect to each other, theupper ends of the stems 18 and 25 being connected forproducing thebalanced action, as will now be described.

Preferably from the upper end of the casing 11 projects a fulcrum 32,which is bifurcated at its upper end, and in the arms of suchbifurcation is journaled a shaft 33 carrying a block 34 between the armsof said bifurcation. To the block 34 is bolted or otherwise rigidlysecured a spring 35, extending in opposite directions from the block andpivotally engaging at its outer ends the upper ends of the respectivevalve-stems 18 and 25. Each of said valve-stems is illustrated asthreaded into a suitable nut at its upper end, which nut is bifurcatedand incloses the respective free end of the spring 35. However, anysuitable connections may be made between the valve-stems and the spring35. Suitable bars 36 36 are fixed to the block 34 between the arms ofthe bifurcation 32, and said arms 36 are secured upon the opposite sidesof an operating-lever 37, which lever naled in the standard 40, mountedupon the casing 41 of a solenoid 42. The flexible connecting means 38extends downwardly from the pulley 39 and at its end opposite thatengaging lever 37 engages the core or plunger 43 of the solenoid 42. Abrass or other nonmagnetic cylinder 42 is arranged within the winding ofthe solenoid 42 and surrounds the plunger 43' and extends a suficientdistance above the winding to prevent the possibility of sticking of theplunger against the cap of the casing 41.

The solenoid 42 may be of any preferred type and may, if desired, takethe form of an ordinary electromagnet, it being understood that thesolenoid may be termed an electromagnet, as the solenoid is consideredby me as one species of the general class of electromagnets. It ofcourse will be obvious that an armature might be substituted for thecore 43 with no suggestion of invention over the present structure, andI propose to utilize either the armature or the moving core, as ispreferred. For the purpose of concentration of the lines of force Ipreferably inclose the winding 42 in the casing 41, which is of softiron or other magnetic material, while the standard 40 is preferably ofbrass or other non-magnetic substance. The solenoid 42 rests upon anypreferred base 44, carried by brackets 45 45, connected to the pipe 1. Aweb 46 connects the brackets 45 at a point contiguous to the base 44,and a bar 47 extends therethrough and has threaded upon its lower end awing-nut 48, adapted to be threaded up against the web 46 for adjustingthe rod 47 longitudinally. The upper end of the rod 47 connects with atension-spring 49, and said spring 49 at its upper end engages the lever37 near. the point of engagement of the chain or cable 38. Thus it willbe seen that the weight of the core 43 is counterbalanced by the Weightof the lever 37 and by the action of spring 49, the tension of spring 49being governed by the wing-nut 48 and being maintained preferably atthat point, producing an equal balance of the core 43.

As will be hereinafter fully described, suitable mechanismis providedfor closing the circuit of the electromagnet 42, which mechanism servesto maintain the circuit in abroken condition until the pressure of steampassing through the pipe 1 or the steam within the boiler being heatedby the furnace supplied with air by the steam passing through the pipe 1hasarrived at the desired degree, when the circuit will be closed, theplunger 43 drawn downwardly, and the lever 37 elevated. Here it is to beobserved that the stroke of the core 43 produces a relatively lon strokeof the end of lever 37 engaged by exible connection 38, while theopposite end of said lever needs only to move a relatively shortdistance, so that the difference in the distance of movement of thepivoted end of the lever 37 relative to the movement of the free endmust mean an increase in the power of such limited movement, so that thevalve-stems 18 and 25 may be moved against a relatively greatresistance. With the high-pressure steam being utilized it is necessarythat the packing within the boxes 20 and 26 must be pressed down until arelatively great friction is caused, and this friction is overcome byreason of the fact that movement of the valves 19 and 27 is onlyrelatively small compared with the moved ment of the core 43, so thatthe force with which the core 43 is drawn downwardly will be multipliedin a ratio proportionate to the difference in distance of the travel ofsaid plunger and the travel of said valves. For the sake ofillustration, assuming that the valves 19 and 27 have a stroke ofone-eighth of an inch and the core 43 has a stroke of one inch, it willbe observed that the force with which the core 43 moves will bemultiplied eight times as applied to the valve-stems 18 and 25. Ofcourse it will at the same time be apparent that the power transmittedfrom the core 43 to the valves 19 and 27 will be decreased to the extentof the resistance of sprin 49, the amount of power with which the punger 43 is drawn downwardly minus the resistance of the spring 49 beingmultiplied relative to the length of the lever 37. This multiplicationof power by reduction in the length of the stroke makes possible theovercoming of the friction occasioned by the packing within thestuffing-boxes 20 and 26 by a comparatively weak magnet. If the lengthof stroke of the valves 19 and 27 were reduced to one-sixteenth of aninch while the core 43 moves an inch, the power of the core, minus thepressure of spring 49, would be increased sixteen times. The ratio ofcourse will be maintained with any alterationin the distance of strokeof the valves 19 and 27 rela-,

tive to the length of stroke of the'core 43, the

only difference in apparatus with cores having various lengths of strokebeing the difference in the length of lever 37 The spring 35 ispreferably relatively stiff,

so that the stem 18 will normally be moved with the, movement of lever37; but'said spring 35 is sufliciently resilient to permit one of thevalve-stems to be moved to a greater extent than the other. Forinstance, if by wear or from other causes the relative position of thevalves 19 and 27 and valves 23' and 29 should become slightly changedwith respect to each other and their seats, so that,

for instance, the valve 19 should become seated upon the downward strokeof the core 43 before the valve 29 has become seated,

further movement of the lever 37 will not be" arrested; but the spring35 will permit the valve 29 to be forced downwardly to its seat. The armof the spring 35 which engages valvestem 18 will be sprung sufficientlyoutof its normalposition to accommodate the necessary movement of thestem 25. Of course the foregoing is merely given as illustrative of theoperation of spring 35, and said spring may of course serve to permitthe valve 19 to take its seat should the valve 29 become seated beforethe lever 37 has completed its stroke. In other words, while the valves19 and 27 and valves 23 and 29 and their stems are adjusted to taketheir seats with respect to each other without any giving on the part ofthe spring 35 and the adjustment of said valves and connecting parts ismade so accurately ordinarily that the spring 35 will maintain itsnormal position with one of its arms extending in line with the other iffrom any cause the said adjustment should become deranged the spring 35will maintain the balanced valves in operative condition, the arms ofthe spring 35 moving out of line with the other whenever necesary foraccommodating any required extra movement occasioned by any slightderangement of the adjustment of the balanced valves. Assuming,therefore, that the valves are perfectly adjusted, the downward movementof the actuating element of the electromagnet will elevate the free endof the lever 37 and will cause the valve 19 to take its seat, the valve27 of course leaving its seat, the valve 29 taking its seat, and thevalve 23 leaving its seat, so that the steam within the upper end of thecylinder 5 may be exhausted past the valve 23 out port 21, and livesteam may enter the lower port 7 past the valve 27, which steam willeffect upward travel of the piston 6, elevating and closing the valve 2,so that the su ply of steam within the pipe 1 is cut off or ot erwisecontrolled, according to the particular adaptation'of'the controllingmechanism above set forth. Upon-decrease of the pressure within theboiler being heated or at any predetermined condition thecircuit-closer, hereinafter described, will break the circuit ofthemagnet 42 and release the core 43, permitting the lever 37 to be drawndownwardly under the action of spring 49. The downward stroke of thelever will unseat the valve 19, will cause the valve 23 to take itsseat, will unseat the valve 29 and cause the valve 27 to take its seat,so that the steam within the lower end of the cylinder 9 will escapethrough exhaust-port 31 and live steam be admitted through the upperport 7 into the upper end of the cylinder 5 for moving the piston 6downwardly and. again opening the valve 2.

As above suggested, I propose to provide a circuit making and breakingapparatus which shall control the electromagnet 42 and cause the same tobe energized whenever the required pressure has been attained. Of courseany of. a series of various forms of thermostats or other contact-makingand breaking apparatus might be employed; but I preferably utilize astructure, such as is dis-- closed in Figs. 5, 6, and 7, in which'50indicates a base of non-conducting material, to which is secured apreferably metallic disk 51. Bolted or otherwise rigidly secured to thedisk 51 is a pipe-coupling 52, communicating with a coiled-pipepressure-gage53, the said gage 53 being rigidly connected to thecoupling 52 and curving about the disk 51, referably normally concentricthereto and'fiaving its end opposite that engaging the coupling 52 freeto move relative to the amount of pressure within the gage.

ply pipe 52 connects with the coupling for supplying pressure to thegage 53. To the free end of the gage 53 is secured arod54',

A pressure-suphaving its free end extending intoa plunger 55, movablymounted within a cylindrical casing 56; A slot, 57 is formedlongitudinally within the casing 56, and: a screw 58 or other securingmeans is passed through the plunger 55 into engagement with the endofthe rod 54 for locking said rod andplunger together, the said screwextending outwardly into the slot 57 and being movable longitudinallythereof. At the opposite end-ofthe cylinder 56'is preferably fixedaninsulating-block 59, .into whichextends the rod 60, similar in con--struction=to the rod 54. I A sprin -61 is disposed between the block 59and t e plunger 55, said spring being of sufficient length for making itnecessary to compress the same when assembling the parts inordertoinsert the screw 58 into the plunger 55through the slot 57, so that saidplunger is normally pressedoutwardly by the spring and maintains thescrew 58 in contact with the outer end of the slot 57. The outer end ofthe rod- 60 pivotally engages a contact-arm 62 ,which arm is journaledon a stub-shaft 63 and is insulated therefrom by a suitable insulation64,

the lower end of the arm 62 being adapted to carry an electricalconductor 65, constituting a part of the circuitofmagnet42. An arm 66 isjournaled upon the shaft 63 in a similar manner to arm 62 and isinsulatedfrom the arm 62 by a suitable insulating-washer 67, the lowerendof'the arm '66, carrying-an electrical conductor 68, alsoconstituting a part of the circuit of said magnet. v the arm 66terminates in a segment 69, anda spring 70 is fixed to the base 50 andpositioned for normally enga segment. A suitable hand e 71 is preferablyformed atthe outer end of'the spring 70 for facilitating. depressing ofthe spring for releasing engagement thereof with the segment. Anysuitable knob or handle 72 is connected with the arm 66 for facilitatingmanual moving of the same upon its pivot... At the upper ends of thearms 62-and 66 is arranged auiding-block 73, formed with itsundersurface struck on the arc of a circle, as clearly seen in Fig. 5, saidblock being formed with parallel grooves 74 74, into The lower end-0f;

ing the eriphery of said which the ends of the arms 62 and 66 extend,the grooves thus serving to guide the arms in their movement. A pin orother suitable device 75 extends laterally from the arm 66 into the pathof movement of a lug 76, extending from arm 62, it being of courseunderstood that the arms 62 and 66, the lug 76, and the pin 75 areelectrical conductors.

In operation the arm 72 may be adjusted to any desired position, and asthe pressure increases within the gage 53 the arm 62 will be swung uponits pivot, due to the outward movement of the free end of the gage 53,such outward movement of the gage of course occasioning longitudinalmovement of the bar 54, which operation through the action of theplunger 55 tends to compress the spring 61 but as said spring hasalreadybeen partially compressed the same will have sufiicientresistance to occasion longitudinal movement of the casing 56 andconnected parts, so that the arm 62 must swing upon its pivot. Thisoperation continues until the pressure has arrived at the maximum, whichmaximum of course is governed by the position of the arm 66. Uponarriving at this point the pressure is suflicient for having caused thegage 53 to move outwardly to a sufiicient extent for causing the lug 56to engage the pin 55, whereupon current will flow, for instance, fromthe battery (seen in Fig. 3) through conductor 65, arm 62, lug 76, pin75, arm 66, conductor 68, through the Winding of magnet 42, and thenceback to the battery. The supply of steam for producing forced draft isthus out 01f by the operation of the mechanism above described, and whenthe temperature of the furnace has dropped to a sufficient degree formaking any appreciable decrease in the pressure within the boiler thefree end of the gage 53 will begin to move inwardly, effecting abreaking of the circuit above described, which operation willimmediately open the steam-supply pipe. This operation will normallycontinue; but if for any reason as, for instance, the polarization ofthe cells of the battery or the breaking of the circuit by accident-theelectromagnet should not be energized upon contact of the lug 76 withpin 75 the upper end of gage 53 may continue to move outwardly, simplyresulting in compressing the spring 61 until the screw 58 arrives at theopposite end of slot 57 from that usually occupied. If normal conditionshave not been restored and the pressure c0ntinues to increase, furtheroutward movement of the free end of gage 53 will be accommodated byreason of the fact that sufficient pressure upon the arm 76 will causethe arm 66 to drag or move upon its pivot against the pressure of thespring 76. Thus it will be observed under ordinary conditions that thecircuit of the electromagnet will be closed in proper time, and underexceptional conditions provision is made for preventing source ofelectrical energy, a lever adapted to be actuated by said magnet, adraft-controlling valve, a piston connected therewith for operating thesame, a cylinder inclosing said piston, admission and exhaust valves forsaid cylinder and yieldable connections between said lever and saidadmission and exhaust valves.

2. In a draft apparatus, the combination with a draft-controlling valve,a piston connected therewith, a cylinder inclosing said piston, intakeand exhaust valves for said cylinder, a lever for actuating said intakeand exhaust valves, an electromagnet adapted to operate said lever, anelectrical circuit including a source of electrical energy and saidmagnet, pivotally-mounted arms interposed in said circuit and adapted tobe brought into contact for closing the circuit, one of said arms beingformed with a segment at its lower end below the point of its pivot, afiat spring fixed in a substantially horizontal .plane in position forhaving its flat face engage the periphery of said segment, and apressure-gage adapted to swing the other arm into contact with the armprovided with a segment.

3. In a draft-controlling apparatus, the combination with means forgoverning the draft and electrical means for actuating said governingmeans, of a pivotally mounted arm interposed in the circuit of saidelectrical means, a gage, and cushioning means connecting the gage withsaid arm for imparting movement from the gage to the arm for effecting aclosure of said circuit upon a given movement of the arm.

4. In a draftcontrolling apparatus, the combination with means forgoverning the draft and electrical means for actuating said governingmeans, of. a pivotally-mounted arm interposed in the circuit of saidelectrical means, a gage spaced from said arm, a bar connected with saidarm a bar engaging said gage, a sleeve inclosing the ends of said bars,a spring within said sleeve interposed between said bars for receivingthe pressure from one of the bars for actuating the other for movingsaid arm in position for closing said circuit,

5. In a draft controlling apparatus, the combination with means forgoverning the draft and electrical means for actuating said governingmeans, of a pivotally-mounted arm interposed in the circuit of saidelectrical means, a gage spaced from said arm, a bar inclosinlgpivotally" connected with said gage, a bar pivotally connected with saidarm, a sleeve surrounding the free ends of said bars, a plunger carriedby one of said bars, an insulating block carried by the other of saidbars, said sleeve being slotted longitudinally, a pin extending fromsaid plunger through said slot, and a spring interposed between saidplunger and insulating block, whereby movement may be imparted from saidgage to said arm for swinging the same into position for closing thesaid circuit.

6. In a draft-controlling apparatus, the combination with means forgoverning the draft and electrical means for actuating the same, of apair of pivotally-mounted arms interposed in said circuit, a segmentcarried by one of said arms, a spring engaging the said segment forfrictionally supporting the arm carrying the segment in any givenadjusted position, a gage, and means connecting the same with the otherof said arms for swinging the last-mentioned arm into contact with thesegment-carrying arm for closing said circuit.

7. In a draft apparatus, the combination with a pressure-gage and anelectric circuitclosing means connected therewith, of an electriccircuit, adapted to be closed by said gage, including an electromagnetand a source of electrical energy, a draft-controlling valve, a pistonconnected therewith, a cylinder inclosing said piston, intake andexhaust valves for said cylinder, spring-arms connected with saidvalves, and means adapted to be actuated by said electromagnet formoving said arms for operating said intake and exhaust valves.

8. In a draft apparatus, the combination with a gage and an electriccircuitclosing means connected therewith, of an electric circuitconnected with said closing means, including a source of electricalenergy and an electromagnet, a draftcontrolling valve, a pistonconnected with said valve, a cylinder said piston, intake and exhaust rsaid cylinder and yielding operating means for said intake and exhaustvalves adapted to be actuated by said magnet.

9. In a draft apparatus, the combination with a pressure-gage and anelectric circuitclosing means, of an electric circuit connected valvestake and exhaust valves for transmitting a cushioned movement from thelever to the valves.

10. In a draft apparatus, the combination with a draft-controllingvalve, pressure-actuating means for operating the same, admission andexhaust valves for said pressure-actuating means, a lever for operatingsaid admission and exhaust valves, an electromagnet adapted to operatesaid lever and an elec- :trical circuit including said magnet and asource of electrical energy, a pair of arms pivotally mounted andinterposed in said circuit, means frictionally resisting pivotal{movement of one of said arms and a pressuregage connected with theother of said arms or swinging the same into contact with thefirst-mentioned arm.

11. In a draft apparatus, the combination with a draft-controllingvalve, a piston connected therewith, a cylinder inclosing said piston,intake and exhaust valves for said cylinder, a lever for actuating saidintake and exhaust valves, an electromagnet adapted to actuate saidlever, an electrical circuit including a source of electrical energy andsaid magnet, pivotally-mounted arms interposed in said circuit andadapted to be brought into contact for closing the circuit, one of saidarms being formed with a segment, a springdrag engaging the periphery ofsaid segment for frictionally resisting pivotal movements of said armand a pressure-gage adaptedto swing the other arm into contact with thefirst-mentioned arm.

In testimony whereof I hereunto afi'lx my signature in presence of twowitnesses.

WILLIAM MoCLAVE.

Witnesses:

JOHN L. FLETCHER, ARTHUR L. KITCHIN.

